Support a limit parameter for holders, voters & delegations routes

[poplexity]

Description

Currently it defaults to 500, should support a limit parameter so you can get more/less

Tasks

• Implement limit in holder route
• Implement limit in voter route
• Implement limit in delegation route

[tomtomcrypto]

Added it to voters & delegations too (ie: a delegator like ecoinairdrop has tens of thousands of results), also added offset for pagination. Max is set to 500, default is 100.
Only problem I can't seem to fix is ordering the path parameters before the query parameters on the swagger UI...